Unless you have three other family or friends profiles already on your Xbox you will need to create them yourselves to obtain this achievement (from your dashboard).
When you're ready to go, load up the game starting with your profile (although not essential with this achievement as you'll see). Choose any contest to play and finish it. While you're at the results page (where you can 'retry' or 'finish') raise your left arm sightly to bring up the main menu and select 'Change Identity'.
Sign in the second profile then select 'retry' and play the same contest again. Repeat twice more at the results screen for the remaining 2 profiles and once the last person (or you if you're doing it on your own) finishes his/her game the achievement will pop for ALL FOUR players.